Although radios are common enough and cheap, why not make your own from a few readily available components? For example, the design shown in Fig is uncomplicated thanks to the two integrated circuits, IC1 and IC2, and it will receive radio stations transmitting amplitude modulated (AM) radio frequencies, delivering your selection to a small loudspeaker.
Circuit Details :
The central component for the first building block is integrated circuit IC1, a ‘radio on a chip’. Essentially, its purpose is to amplify the small volt- age generated across the tuned circuit comprising the LC combination; that is, variable tuning capacitor VC1 in parallel with inductor L1. When the radio is ‘tuned in’ to a station by adjusting VC1, a small alter- nating voltage is generated across the tuned circuit. This is processed by the rest of the circuit to extract the informa- tion carried by this carrier wave. IC1 requires a 1.5V supply voltage, which is provided by transistor TR1, resistor R1 and potentiometer VR1, used as a variable resistor. Adjust- ment of VR1 alters the supply voltage and determines the sensitivity of the circuit. Capacitor C2 couples the signal from the radio frequency amplifier and detector stage to the second building block, a low-power audio amplifier based on IC2, which powers a small loudspeaker, LS1. Potentiometer VR2 acts as a volume control.